Q. “A wicked and adulterous generation seeketh after a sign; and there shall no sign be given unto it, but the sign of the prophet Jonah. And he left them, and departed.” Matthew 16:4. For as Jonah was a sign unto the Ninevites, so shall also the Son of man be to this generation.” Luke 11:30.
Can you give me an explanation of what exactly is the Sign of Jonah?